Initial
researches in connection with development of 203-mm self-propelled
artillery gun capable of firing in 25 kilometer range began in Soviet
Union in the December of 1967. Such gun was intended to defeat separate
very important ranged objects, destroy fortifications and fire special
nuclear projectiles. In the March of 1970 there were enumerated
tactical-technical characteristics for such artillery gun's development
and in the late 70-ties first serial 2S7 "Pion" Self-Propelled
Artillery Guns were provided for Soviet Union special extremely powerful
artillery brigades. Recently the 2S7 "Pion" is in service with
Russian and some other CIS countries and also Poland Czech Republic and
Slovakia.
The 2S7 has the longest range of fire comparing with any other modern
field artillery unit and also it is the largest self-propelled artillery
gun in the world.

The
2S7 "Pion" Self-Propelled Gun features turretless design with
rear opened placed main gun. Driving compartment is in the front
section and engine-transmission compartment is right behind it and crew
compartment and combat compartments go further. Artillery unit's crew is
14 men. On march 7 of them are carried by self-propelled artillery gun
while others in convoying truck or armored personnel carrier.

Commander and driver have
their seats in the driving compartment. Cabin is protrudes forward
creating counterweight for the main gun. Cabin
features two roof hatches. Forward observation is provided threw the windscreens or periscope
observation devices. However windscreens can be covered with an armored
shutter. There is also a forward-facing periscope in the forward part of
the roof between commander and driver. In the combat position gunner seats
at the rear of the hull on the left side. Gunner operates elevation and
traverse controls.

At the rear part of the hull
there is very powerful 2A44 the 203-mm artillery gun. Gun has no muzzle brake. This
design decision was caused of a low pressure dangerous for crew while
mounting muzzle brake some additional protection measures had to be taken.
Gun's lock is automatically opened and closed by a special mechanical
device. However this operation can be done manually in emergency
situation. Projectile and load are loaded by load-assisting mechanism.
This loading mechanism works in any gun's elevation and traverse
inclination levels. Loading operations are made from locker's deck.

Over and under the gun there
are mounted hydro-pneumatic recoil absorbers. Recoil step is approximately
1 400 mm. The 2S7 "Pion" is completed
with rear mounted
bulldozer type hydraulic operated spade. It digs in the ground
approximately 700 mm and provides good fire stability. Fire
stability is
also ensured by landing directing sprockets
and blocked wheels hydro
absorbers. All these features allow to
fire in a wide range of elevation
and traverse ranges. Elevation range is between 0° and 60° and traverse
range is 30° (15° to the each side). In a low elevation levels or using
low power loads fire is executed without lowering spade and other recoil
absorbing measures.

Ammunition is separately
loading type. The main is OF43 High-Explosive Fragmentation Projectile and
rocket assisted projectile. High-explosive fragmentation projectile
weights 110 kilograms and consists 17.8 kilograms of explosives. Such
projectiles maximum range of fire with a normal load is 37.5 kilometers
and initial speed - 960 m/s. Rocket assisted projectile weights 103
kilograms and contains 13.8 kilograms of explosives. It's range of fire is
a record for a modern field artillery and is 47.5 kilometers.

Without already mentioned
ammunition the 2S7 "Pion" Self-Propelled Artillery Gun fires
concrete piercing, chemical and also tactical-nuclear projectiles. Combat
load consists from 40 rounds however
only 4 of them are carried by self-propelled
artillery gun for immediate use and remaining - by convoying vehicle.
In fire position ammunition is
lowered to the ground and carried to artillery
unit using
one-axis barrow.

Maximum rate of fire is 1.5
rounds per minute. However there are intended later firing modes:

Especially for the 2S7
Artillery Gun in Leningrad (now St. Petersburg) Kirovsk Plant there was
developed and produced special tracked chassis (object 216). Exactly this
plant made final assembling of the 2S7. It's artillery part was supplied
by "Barikady" Plant. Vehicle is powered by
V-46-1, the V-type
12-cylinder diesel engine completed with turbocharger. It reaches maximum
power of 750 hp. Furthermore "Pion" is fitted with auxiliary 24
hp. diesel engine for autonomic electricity supply. Mechanic transmission
with a conical reducer and board gear boxes are similar to the T-72
Main Battle Tank.

Chassis features 7 doubled
rubber wheels and 6 supporting rollers mounted from the each side. Wheels
suspension is individual, torsion with stopping hydro absorbers. Driving
sprocket is placed front and the rear sprocket is lowered to the ground in
combat order. A great number of chassis elements are similar
to the T-80 Main Battle Tank.

The 2S7 "Pion"
features quiet high mobility for a such mass vehicle. Considering that
preparing for the march position time is set to minimum, artillery unit in
principle is able to fire 1-2 rounds and leave it's position while the
first round will defeat target in 47 kilometers range.

Vehicle is equipped with a
tank internal communication device, radio equipment and fire prevention
equipment. In addition it is completed with nuclear, biological, chemical
protection system and night vision equipment.

During the 2S7
Self-Propelled Artillery Guns improvement works in 1983 it was
additionally fitted with data receiving and monitoring devices. During the
improvements rate of fire was increased to 2.5 rounds per minute and
carried ammunition load was increased to 8 projectiles with loads.
Improved self-propelled artillery gun is designated as 2S7M "Malka".

Advantages

The 2S7 has the longest range of fire
comparing with any other modern field artillery unit. It is able to fire
and leave position before projectile hits target. Powerful projectiles.
Some mechanisms are interchangeable with a widely used T-72
and T-80 Main Battle Tanks.

Disadvantages

Low chassis service life.
Out-dated fire control equipment (only with not improved models). Only
some projectiles can be carried by artillery unit itself for immediate
fire.